Combining Modeling and Measurements To Predict Crystal Morphology in Material Extrusion

McIlroy, Claire and Seppala, Jonathan E. and Kotula, Anthony P. (2019) Combining Modeling and Measurements To Predict Crystal Morphology in Material Extrusion. In: Polymer-Based Additive Manufacturing: Recent Developments. American Chemical Society, pp. 85-113. ISBN 9780841234260, 9780841234253

Full content URL: http://doi.org/10.1021/bk-2019-1315.ch006

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Combining Modeling and Measurements To Predict Crystal Morphology in Material Extrusion

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Abstract

Semicrystalline polymer melts are commonly used in material extrusion (MatEx) for 3D printing. Although flows have a profound effect on polymer crystallization, the relationship between typical MatEx deformation rates and printed-part crystal morphology is yet to be understood. Here, MatEx is used to print a wall of polylactic acid filaments. The linear rheology and quiescent crystallization kinetics are characterized, infrared imaging is used to measure temperature variations during the MatEx process, and optical microscopy is employed to determine the resulting crystal morphology before and after a postprinting thermal annealing process. Our flow-enhanced crystallization model demonstrates that MatEx-induced polymer stretch leads to a higher nucleation density and greater space filling in the weld regions between deposited filaments. Consequently, after annealing, the weld regions feature smaller spherulites than the filament center, as shown by optical microscopy. Finally, flow-induced crystallization is proposed as a method to improve weld toughness.

Keywords:Material Extrusion, 3D printing, semi-crystalline polymer melt, polylactic acid, annealing, flow-enhanced crystallization
Subjects:F Physical Sciences > F290 Materials Science not elsewhere classified
G Mathematical and Computer Sciences > G150 Mathematical Modelling
H Engineering > H990 Engineering not elsewhere classified
F Physical Sciences > F200 Materials Science
G Mathematical and Computer Sciences > G120 Applied Mathematics
G Mathematical and Computer Sciences > G160 Engineering/Industrial Mathematics
Divisions:College of Science > School of Mathematics and Physics
ID Code:36885
Deposited On:05 Sep 2019 10:51

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